"We definitely need a medication to help people reduce methamphetamine use and that's a big gap in our knowledge at the moment, we do have other treatment options that are available to people and they will always be needed," she said.

"It's not the case that this particular drug is going to solve all our problems related to methamphetamine.

"[But what we haven't got at the moment is a medication that people can take to help them reduce their cravings for the drug.

"This substance, NAC, if it does work to reduce cravings and reduce use, will make a potentially cost-effective treatment available to people who want to stop using the drug."

The National Drug Research Institute is leading the trial which is taking place in Melbourne, Geelong and Wollongong, in collaboration with various universities.

About 180 people who want to reduce their methamphetamine use will be recruited, and they will be put on NAC for 12 weeks.